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Physics for a Dummy

MN_Bowhunter4

MN_Bowhunter4

Well-Known Member
Joined
Jul 16, 2018
Messages
992
Location
Minnesota Metro
Backstory, I was given my dads recurve last summer, a kodiak hunter #50. I am really shooting it hard this spring and summer so that I can be comfortable taking it on stand this fall.

Shortly after getting it I went to 3Rivers to order arrows. Their chart said I needed 400 spine, so I got them cut to 29.5”. As I’m shooting now, they fly like crap and stick every which way in the target. However, some full length 450s I have laying around fly like darts. What is happening here, in layman’s terms? I tried both a 100 and 125 gn field point on both sets and same result.

I know I’m sticking with the 450s, but curious why they are shooting like that?
 
Because Traditional spine charts/calculators always recommend a heavier spine than what is needed. The best way is to get a test kit of shafts and field tips and try a bunch of different weights and spines to see for yourself what actually flys and what doesn’t.
 
Lots of guys shoot full length carbons or near full length.
I would not cut a shaft ever other than in tuning and then little by little.
The other thi g is guys will shoot into bag targets or targets that do not allow the arrow to show it's TRUE attitude at impact and in some cases hang downward.
Take every chance to shoot others arrows out of your bow. Occasionally you find one that flies real good and then you can go ahead and cut to build to that spec.
The 400s were already stiffer than the 450s at full length and cutting them made them stiffer.
 
I’m just getting into trad and I’d always just cut to length for compound so that’s what I did! Makes sense though. The weird thing is I can actually see the 400s fly all crazy, and when they impact the target they stick pretty good, not hanging, just nick pointing every which way!
 
You spine is too stiff. Your arrow wants to fly knock right but it can't because the bow is in the way. Arrows going every which way probably mean collision, otherwise you should see a consistent defect. The 450's flex (more) correctly and spring off the shelf to let the fletch clear more cleanly. Try some more tip weight on the 400's ...... . Put 150 or 175 upfront and see how they do. I second the bareshaft suggesstion.
 
The 50# rating is at a certain DL, if your over that you’d need stiffer arrow, shorter - less. With
Traditional setup it’s trial and error sometimes, esp with a heavy front end.


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On this same vain I was slinging a few bareshaft aluminums since they were available locally and cheap and I found that the 2213’s were flying the straightest. Going on Easton’s website it shows that the spine for the 2213’s at 28” was .458”. Does the span deflections measurement correlate to the spine values you see on other arrows? I.e. does .458” mean ~450 spine? How much do you think that the spine is varying if I draw over 28”?
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put a clothes pin on the arrow, then draw as you were going to shoot. let down and measure from groove in knock to clothes pin.........thats your draw length.
 
arrow30 said:
put a clothes pin on the arrow, then draw as you were going to shoot. let down and measure from groove in knock to clothes pin.........thats your draw length.
Click to expand...
I was wondering if it was that simple or not....................if that’s the known standard/consensus then I have ~29.5” draw length.
 
There are several variables here that all play their part in your findings.

1) Don't assume all .400 spined arrows are .400 spine.
2) The nock fit could vary.
3) Your release could vary day to day, or even shot to shot(one reason a mechanical release is used with compounds, consistency).
4) Arrow diameter - the thicker or thinner an arrow is, it will require some adjustment.

IF you have access to an arrow saw, I would always encourage you to order full lengths and then tune the arrow to the bow.
 
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